The broad objectives are to study the biomechanics of "loud" or "heightened" speech, and to study how it can be safely trained in individuals with phonotrauma, who need it for their work Loud speech traditionally has been viewed as an anathema for vocal health. In this application we hold an opposing view that specialized approaches to loud voice training not only may prevent injury; some approaches actually may have therapeutic value in the treatment of both acute and chronic injury. In these studies, we focus on teachers, who represent the most common occupation in the United States. Teachers experience near epidemic proportions of voice problems, traceable prolonged, loud speech on the job. Functional consequences of such problems include reduction and loss of work, and reduced cognitive functioning for students. Societal costs appear to range in the billions of dollars annually in the U.S. Thus, a study of safe--and even therapeutic loud speech in this population is both critical and timely. We initiate our studies by investigating biomechanical factors that influence vocal loudness operationalized as radiated voice output power. Specific Aim #1 assesses whether recent, non-linear simulation models of loud speech production apply to human subjects, by measuring variations in radiated output power as a function of epilaryngeal-to-glottal cross-sectional area ratios. We use Single-Shot Fast Spin Echo (SSFSE) Magnetic Resonance Imaging (MRI). We expect to replicate theoretical findings that impedance-matched vocalization conditions--in particular those involving neutral epilaryngeal and glottal areas found with "resonant voice"--will maximize output power, while at the same time limiting damaging vocal fold impact stress. Specific Aim #2 assesses the utility of "resonant voice" exercises for the reversal of acute phonotrauma. The primary dependent variable is concentration of inflammatory markers from laryngeal surface secretions, and secondarily, aerodynamic and perceptual measures. Finally, Specific Aim #3 examines the effect of "resonant voice" training for teachers with chronic phonotrauma, using a randomized, prospective clinical trial. We will deliver a standardized resonant voice therapy program and a control treatment to teachers with phonotrauma. The primary dependent variable is quality of life in relation to voice, measured with the Voice Handicap Index. Secondary variables are aerodynamic, laryngeal, and vocal quality measures. [unreadable] [unreadable]